Current supply for luminescent diodes

ABSTRACT

A regulation circuit is provided for making available a constant current supply on the basis of a transformer principle, in which there flows through the luminescent diodes a triangular a.c. current varying periodically around a d.c. current value. Circuitry is provided so that both the charging and the discharging current of an inductive reactance connected in series to the luminescent diodes, functioning as a storage choke for filtering of mains harmonics, flows as diode current through the luminescent diodes. An advantage of this method consists in a significant reduction of the overall power loss of the LED illumination module. According to one embodiment, the ceramic circuit board of the LED illumination module has a direct mains current supply, which, for protection from mechanical damage, is accommodated in a transparent housing having a highly transparent polymer mass serving as an optically active lens surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Continuation of application PCT/EP03/06952 filed on Jun. 30,2003, and published in German but not English as WO 2004/006629 A2 onJan. 15, 2004, the priority of which is claimed herein (35 U.S.C. §120)and which claims priority of German Application No. 102 30 103.4 filedJul. 4, 2002, the priority of which is also claimed herein (35 U.S.C.§119).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a current supply for LEDs. Thereby, atransformer principle is put to use which generates a triangular a.c.current, which varies periodically around a d.c. current value, throughthe luminescent diodes. By means of this process it is provided thatboth the charging and also discharging current of an inductive reactancein the load circuit flows as diode current through the luminescentdiodes.

2. Description of the Related Art

High-power light emitting semiconductor luminescent diodes(“Light-Emitting Diodes”, LEDs), briefly referred to as light diodes,have long since achieved their place in many fields in which there isneed for optical display systems or illumination systems having lowenergy consumption, such as e.g. in traffic and signaling technologies.Through decisive technical innovations in the field of light emittingsemiconductor components, with the aid of which there can today beobtained a higher light yield and an extension of the color spectrumover the entire wavelength range of visible light between 780 nm(violet) and 380 nm (dark red), optoelectronics is, in terms of lightingtechnology, embracing completely new markets.

For the attainment of a uniform illumination of surfaces, diffuserplates are employed as a rule. Due to the mains operation, above all incase of outdoor applications, light housings are usually necessary inorder to protect the electronic components employed from the penetrationof moisture.

In order to understand the central idea of the present invention, therewill be briefly explained below the most important features ofconventional processes and technologies according to the state of theart for the production of semiconductor luminescent diodes, above allthe so-called “Chip-On-Board” (COB) Technology, which has greatlyincreased in significance in the last few years.

In “Chip-On-Board” (COB) Technology, the raw LED-chip is applied to thecircuit board, with conductive adhesive, with the structure and theterminals upwards (“face up”). This procedure is called, inAnglo-American terminology, “die bonding”. After the curing of theadhesive there is effected in a further working step the connection ofthe chip terminals with the circuit board with the aid of a wire bonder,known from the production of integrated circuits. Thereby, theindividual chip terminals and the circuit board are connected by a goldwire. Through the employment of special circuit board materialsexcellent heat conduction properties can be attained. From this thereresults a longer working life and a higher light yield per unit area.After application of a polymeric layer, the LED array is protected frommechanical damage due to shock or vibrations. Special circuit boardswith reflector layers thereby serve for light bundling and increase oflight intensities at smaller emission angles.

In comparison to conventional LED modules, through the employment ofluminescent diodes which are applied to a circuit board as an LED arrayby means of COB technology, there can be produced efficient illuminationunits of high light yield, long working life, space-saving constructionand a relatively slight cost outlay. Due to the light current valueswhich can be attained, these modules are interesting not only assignalling or background illumination, but can be directly put to use asillumination means. LED arrays produced with COB technology having anemission angle of 180° permit a bright illumination of surfaces with ahomogeneous light distribution, which is comparable with illumination bymeans of illumination equipment with fluorescent lamps operated at 40 to50 mA. A further plus point is the 50% lesser current consumption incomparison with such illumination equipment.

Point light sources formed of high power luminescent diodes with COBtechnologies are ideally suited for small work and reading lights, asflexibly employable light sources in spot illumination, as central lightsource for orientation lights etc.

From DE 100 26 661 A1 there is known a universal compact LEDillumination module which can be employed for indoor and outdoor lightsin mains operation and without employment of further operating devices,such as e.g. mains transformers or specially dimensioned switch powerunit parts. The light emitting semiconductor components provided aslight sources are thereby controlled and supplied with current via acapacitor power unit part. In the preferred embodiment of thisinvention, the light emitting surfaces of the individual luminescentdiodes emerge lens-like from the molding mass. As outer structural formfor the LED illumination module disclosed herein there serves a moldingmass (e.g. a casting resin) or a housing in which the electroniccomponents are mounted protected from the penetration of moisture. Themodule can thereby be operated as a lamp or light directly from acurrent supply mains, can be positioned anywhere, and can beeconomically produced.

In the case of conventional capacitor power unit parts according to thestate of the art (in contrast to the electronic solution in accordancewith the invention) the effective value of the input alternating voltagecan be selected to be variable (e.g. between 100 V_(AC) and 277 V_(AC));even a supply of the mains part with d.c. voltage is possible.

Since, however, in the case of a capacitor mains power unit circuit thesize of the capacitors employed increases strongly with increasingoperating power, only low powers can be realized with such a mains powerunit with acceptable structural size. Further, the performance of theelectrolytic capacitors conventionally employed in the capacitor mainspower units deteriorates with a number of operating hours. For thereasons mentioned above there is needed for the operation of high powerLEDs (having an operating power of up to 4 W) the employment ofalternative electronic solutions.

SUMMARY OF THE INVENTION

Starting from the above-mentioned state of the art, the presentinvention is concerned with the object of providing a current supply forluminescent diodes which can be adapted in simple manner to differentLEDs. Beyond this, naturally, a good efficiency should also be attained.

This object is achieved in accordance with the invention by means of thefeatures of the independent claims. Advantageous exemplary embodiments,which further develop the concept of the invention, are defined in thedependent claims.

The present invention discloses a regulation circuit in accordance withthe preamble of claim 1, which can be adapted in simple manner to theprevailing current demands of an LED.

With the employment of the switching principle in accordance with theinvention, also a plurality of luminescent diodes connected in seriescan be connected to low voltages of more than 30W. The regulationcircuit thereby acts as a constant current source.

The process realized with the aid of this regulation circuit works inaccordance with a transformer principle, with which there flows throughthe LED a triangular current periodically varying around a d.c. currentvalue. Thereby, with the aid of a circuitry provision, it is providedthat both the charging and also the discharging current of an inductivereactance connected in series to the luminescent diodes as a storagechoke flows as diode current through the luminescent diodes. Theadvantage of this procedure consists in a reduction of the overall powerlosses of the LED illumination module.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention will be described in more detail with reference tothe accompanying drawings.

FIG. 1 is an exemplary embodiment of an LED illumination module,comprised of an arrangement of a plurality of luminescent diodesconnected in series, fed with a.c. current via a current supply mains,which are applied on a circuit board as LED dice in a “Chip-On-Board”(COB) technology.

FIG. 2 a is a first variant of a regulation circuit for making availablea regulated current supply for LEDs, in which a signal transfer memberemployed in the feedback branch for galvanic decoupling (potentialseparation) is realized as an opto-coupler diode,

FIG. 2 b is a second variant of the regulation circuit in accordancewith the invention, for making available a regulated current supply forLEDs, in which a signal transfer member employed in the feedback branchfor galvanic decoupling (potential separation) is realized as a level orpotential offset stage and

FIG. 3 is a temporal development of the current flowing through aluminescent diode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, the functions of the component groups contained in anexemplary embodiment of the present invention, as illustrated in FIGS. 1to 3, will be described in more detail. The significance of the symbolsprovided with reference signs in FIGS. 1 to 3 can be taken from theaccompanying list of reference signs.

In FIG. 1, the basic structure of an LED illumination module 100 isschematically illustrated in longitudinal section. It has an arrangementof luminescent diodes D1, . . . , DN, connected in series, fed with a.c.current, which are applied to a circuit board 102 as so called LED dicein a “Chip-On-Board” (COB) technology.

However, the invention can just as well be employed for the control ofother configurations of LEDs and in particular an individual LED.

In accordance with an exemplary embodiment of the invention, the heatconducting ceramic circuit board 102 of the LED illumination module 100has a direct mains current supply, consisting of a mains part 104 and aconnection cable, plug and/or socket 108 for connection to an a.c.current mains led out of the mains part 104 to the side. The luminescentdiodes D1, . . . , DN are accommodated, for protection from mechanicaldamage, in a transparent housing 106 having a highly transparent polymermass 110 serving as optically active lens surface.

For attaining a bundled homogeneous light distribution in the region ofthe main emission directions of the individual luminescent diodes D1, .. . , DN, the LED illumination module 100 in accordance with theinvention further has so-called Fresnel lenses in the form of a lensplate which is positioned centrally above each luminescent diode D1, . .. , DN within the transparent housing, and adhesively fixed at the side.

In order to avoid the occurrence of air bubbles on the side of thecircuit board 102 on which the luminescent diodes D1, . . . , DN areapplied, upon casting of the highly transparent polymeric mass 110within the transparent housing 106, holes are provided in the circuitboard 102. In the production of the LED illumination module 100 theindividual unhoused LED diodes D1, . . . , DN are, within the frameworkof an injection molding process or another suitable molding processdirectly injected around with the highly transparent polymer mass 110.Thereby, the polymer mass 110 is of a thermally good conductingmaterial, which acts in an electrically insulating manner.

Since white light cannot be generated with the aid of individualluminescent diodes there is provided in accordance with the inventionthe addition of a color conversion medium into the polymer mass 110 inthe region of the main emission direction above the position of themonochromatic photon radiation of the luminescent diodes D1, . . . , DNemitting in the spectral range of the color blue.

Due to the space saving arrangement of the employed components and theemployment of the above-mentioned efficient COB production process, thestructural height of the overall arrangement of the LED illuminationmodule 100 in accordance with the invention is not more than for example1.0 cm.

In accordance with one exemplary embodiment of the basic invention, theindividual luminescent diodes D1, . . . , DN are dimmable, whereby fordimming the brightness of the photon radiation emitted from them acontrol via radio or infrared signals or via a microcontroller connectedto a bus is conceivable.

For ensuring a direct mains current supply of the circuit board 102, themains part 104 can in accordance with the invention be operated in avoltage input range from 100V to 277V. Thereby it can also be providedthat the mains part 104 can be operated with a.c. voltage and also withd.c. voltage and along with the operation of individual LEDs can beemployed for operation with serial connected and also for operation withparallel connected luminescent diodes D1, . . . , DN.

The inner sides of the transparent housing 106 (with the exception ofthe light emitting regions) are, in accordance with the invention, of athermally good conducting material that on the outside, used for heatdischarge, is covered with an electrically non-conducting material.Thereby, the transparent housing 106 can be contacted with the aid of aplug, socket and/or connection cable 108 led out of the housing to theside.

In accordance with one exemplary embodiment of the basic invention it isprovided that around each individual luminescent diode D1, . . . , DN,formed as LED die, a parabolic or funnel-shaped reflector of a reflectorplate of a thermally good conducting highly reflecting material, whichreflector plate is electrically insulated on the underside, is placed onthe circuit board 102 from above. Each individual reflector thereby isof a plastic with mirrored inner side.

The rear side of the circuit board 102 is, in accordance with theinvention, coupled to a cooling body, which serves for transferring thedischarge heat arising upon operation of the LED illumination module 100to the housing 106 or to a holder (not shown).

With reference to FIGS. 2 a and 2 b, two variants of a regulationcircuit in accordance with the invention will now be explained.

Via a rectifier full-bridge circuit V1, the positive and/or mainshalf-waves of the a.c. current I_(Netz) delivered from a current supplymains are rectified. At the storage capacitor C1, connected with theearth node, at the output of the rectifier full bridge V1 there is thusapplied a smoothed and rectified intermediate circuit voltage U_(C1)varying with the mains voltage _(Unetz).

After the application of a suitably dimensioned control voltage U_(G) tothe gate of a first semiconductor power switch M1, for example realizedas a self-blocking n-channel MOS field effect transistor, this firstelectronically controllable switching stage is electrically conducting,so that a drain current begins to flow, which as a consequence of thestorage choke L1 acting as an energy store, continuously increases andflows as diode current I_(D) through the luminescent diodes D1, . . . ,DN. The rise of this diode current I_(D) upon charging of the storagechoke L1 is detected by a first low-voltage shunt measurement resistanceR5, which at the same time is arranged in the load circuit of the firstpower switch M1 and in the control circuit of the second power switch Q1and is connected with the earth node. Along with the two power switchesM1 and Q1, in accordance with the invention, a time-dependent controlfor switching over between the charging and discharging processesoccurring in the storage choke L1 may be provided.

This shunt measurement resistance R5 may thereby preferably beconstituted as a potentiometer for dimming the light intensity I_(V)[mcd] (i.e. the brightness), proportional to the diode current I_(D)[mA], of the photon radiation emitted from the luminescent diodes D1, .. . , DN.

Now, as soon as the base-emitter voltage U_(BE) of a secondelectronically controllable switching stage Q1, formed e.g. as a bipolarnpn transistor, reaches in certain switching threshold, thesemiconductor power switch Q1 becomes electrically conducting, so that acollector current I_(C) begins to flow and the gate voltage U_(G) of thefirst electronically controllable switching stage M1 temporally sinks toa “low” level, through which the switching stage M1 is in turn blockedfor a short time. This has the consequence that the diode current I_(D)built up via the storage choke L1 is diverted through a free-runningdiode DF and a second low-voltage shunt measurement resistance R4,connected in series to the free-running diode, in the branch parallel tothe series connection of the luminescent diodes D1, . . . , DN and theinductive reactance X_(L1).

With the aid of this relatively simple circuitry measure a danger to thefirst semiconductor power transistor M1 due to the induction voltageU_(L1) dropped at the inductive reactance X_(L1) upon switching off ofthe drain current I_(D) (upon blocking of the M1), which can amount to amultiple of the operating voltage, is avoided.

The voltage U_(R4) dropping at the low-resistance shunt measurementresistor R4 thereby serves for the detection of the decay of the diodecurrent I_(D) through the luminescent diodes D1, . . . , DN, in thefree-running current path, which is bonded to a minimum value by meansof the switching threshold of the second electronically controllableswitching stage Q1.

After feedback of the diode current I_(D) flowing through theluminescent diodes D1, . . . , DN, tapped at the second measurementresistor R4, to the control input of the first switching stage M1 via asignal transfer member U1 for galvanic decoupling (potential separation)of the voltage U_(R4) dropping at the second measurement resistance R4and the gate voltage U_(G) of the first switching stage M1, thistransferred, decaying diode current I_(D) acts as a “new” gate currentI_(G). This has the consequence that the gate voltage U_(G) of the firstelectronically controllable switching stage M1 remains at the levelvalue “low” and thus the switching stage M1 remains blocked for so longuntil the current flow through the signal transfer member U1 has fallenbelow a certain threshold. After the switching stage M1 has begun againto conduct, the above described procedure is continued in a periodicallyrecurring sequence.

With the process in accordance with the invention, thus both thecharging and also the discharging current I_(L1) of the inductivereactance X_(L1) flow as diode current I_(D) through the arrangement ofthe serially connected luminescent diodes D1, . . . , DN of the LEDillumination module 100 in accordance with the invention, so that thereis provided a triangular current swinging periodically around a middlevalue.

The signal transfer member U1 employed in the feedback branch of thecurrent I_(D) flowing through the luminescent diodes D1, . . . , DN,tapped off at the second measurement resistance R4, to the control inputof the first switching stage M1, which member is employed for galvanicdecoupling (potential separation) of the voltage U_(R4) dropping at thesecond measurement resistance R4 and the control voltage U_(G) of thefirst switching stage M1, may thereby be formed preferably asopto-coupler diode (c.f. FIG. 2 a) or as level offset stage (c.f. FIG. 2b). A Zener diode Z1 here serves as voltage limiter for stabilization ofthe control voltage U_(G) of the first electronically controllablesemiconductor power transistor M1 which can be tapped off at the outputterminals of the opto-coupler diode or level offset stage U1.

In the realization of the second variant of the regulation circuit 200 bin accordance with the invention, with level or potential offset stageU1, there are needed, additionally to the components necessary for thefirst variant 200 a with opto-coupler diode, two transistor stages T1and T2 and a voltage divider which is formed by means of the tworesistances R6 and R7.

In FIG. 3 the temporal development of the diode current I_(D) flowingthrough the luminescent diodes D1, . . . , DN is illustrated. There isinvolved, as illustrated, a triangular a.c. current periodicallyoscillating around a middle value, the frequency of which a.c. currentis determined by the switching thresholds of the control voltages U_(G)and U_(BE) needed for control of the two power transistors M1 and Q1,the size of the inductance of the choke coil L₁ connected upstream ofthe luminescent diodes D1, . . . , DN, and the instantaneous value ofthe intermediate circuit voltage U_(C1) dropping at the storagecapacitor C1. For the example sketched out in FIG. 3, these parametersare so dimensioned that the resulting diode current I_(D) preferably hasa frequency of less than 100 kHz.

The d.c. current offset, forming the middle value of the obtained diodecurrent I_(D), can be set by means of suitable dimensioning of the twoshunt measurement resistances R4, R5, in order to adapt the currentsource to the LED concerned. In this way an economical adaptation of thediode current I_(D) to differing LEDs is made possible withoutadditional circuitry measures.

In contrast to conventional capacitive mains parts in accordance withthe state of the art, the solution in accordance with the invention issubstantially more space saving. Beyond this, also application specificintegrated circuits (ASICs), having a comparatively small spacerequirement, are conceivable.

List of reference signs No. Circuitry symbol 100 LED light strip system,comprised of an arrangement of a plurality of luminescent diodes D1, . .. , DN connected in series, fed via a current supply mains with a.c.current I_(netz?) which are applied to a circuit board as LED dice in a“Chip-On-Board” (COB) technology 102 Heat conductive ceramic circuitboard 104 Mains part for ensuring a direct mains current supply of thecircuit board 104 106 Transparent housing for protection of the circuitboard 102, and the luminescent diodes D1, . . . , DN mounted thereon asLED dice, from mechanical damage 108 Connection cable, plug and/orsocket for connection to an AC current mains, led out to the side fromthe supply part 104 110 Highly transparent polymer mass, placed in thetransparent housing 108, serving as optically active lens surface 200aFirst variant of the regulation circuit in accordance with the inventionfor making available a regulated current supply for an arrangement of aplurality of luminescent diodes D1, . . . , DN of a LED light stripsystem 100, connected in series, applied to a circuit board 102 as LEDdice, fed with a.c. current I_(NETZ) via a current supply mains, inwhich the signal transfer member employed in the feedback branch forgalvanic decoupling (potential separation) is realized as anopto-coupler diode 200b Second variant of the regulation circuit inaccordance with the invention for making available a regulated currentsupply for an arrangement of a plurality of luminescent diodes D1, . . ., DN of a LED light strip system 100, connected in series, applied to acircuit board 102 as LED dice, fed with a.c. current I_(NETZ) via acurrent supply mains, in which the signal transfer member employed inthe feedback branch for galvanic decoupling (potential separation) isrealized as a level offset or potential offset stage. 300 Temporaldevelopment of the current I_(D), flowing through a plurality ofseries-connected high power luminescent diodes D1, . . . , DN of such anLED light strip system, after carrying out the process in accordancewith the invention for regulated current supply for such an arrangementC1 Storage capacitor for making available a smoothed and rectifiedintermediate circuit voltage U_(C1) (varying with the mains voltageU_(NETZ)) at the output of the rectifier full bridge V1 D1, . . . , DNHigh power luminescent diodes (LEDs) of a LED light strip system,connected in series, applied to a circuit board as LED dice, realizedwithin the scope of a “Chip-On-Board” (COB) technology DF Free-runningdiode, connected in parallel to the series connection of the high powerluminescent diodes D1, . . . , DN and the inductive reactance X_(L1) inthe load circuit, for avoiding a danger to the first semiconductor powertransistor M1 due to the induction voltage U_(L1), which can amount to amultiple of the operating voltage, dropping at the inductive reactanceX_(L1) upon switching off of the drain current (I_(D)) (in the case of ablocking of M1) M1 First electronically controllable semiconductor powerswitch, realized as field effect transistor (FET) e.g. as self-blockingn-channel MOSFET having the control voltage U_(G) Q1 Secondelectronically controllable semiconductor power switch, realized asbipolar npn-transistor having the control voltage U_(BE) R1 Low voltagecharge/discharge resistance in the branch parallel to the series circuitof the high power luminescent diodes D1, . . . , DN and the inductivereactance X_(L1) R2 Effective resistance of the ballast choke L₁ R3Series resistance in the control circuit of the bipolar npn-transistorQ1 R4 Second low voltage shunt measurement resistance (“shunt”) -connected in series to the free-running diode DF - for detecting thedecay of diode current I_(D) in the free-running current path, i.e. inthe branch parallel to the series connection of the high powerluminescent diodes D1, . . . , DN and the storage choke, the diodecurrent flowing through the high power luminescent diodes D1, . . . , DNand the storage choke L₁ during a discharge process occurring in thestorage choke L₁, the decay being limited to a minimum value with theaid of the first switching stage M1, R5 First low voltage shuntmeasurement resistance (“shunt”) for detecting the increase of diodecurrent I_(D) flowing through the high power luminescent diodes D1, . .. , DN, which increase is restricted to a maximum value with the aid ofthe second switching stage Q1, the shunt preferably realized as asettable resistor (potentiometer) for brightness dimming of the highpower luminescent diodes D1, . . . , DN, which at the same time isarranged in the load circuit of the first power switch M1 and thecontrol circuit of the second power switch Q1, and is also connectedwith the ground node R6 First resistance of a voltage divider consistingof R6 and R7 for the level or potential offset stage provided as signaltransfer member U1 within the scope of the second variant of theregulation circuit 200b in accordance with the invention R7 Secondresistance of a voltage divider consisting of R6 and R7 for the level orpotential offset stage provided as signal transfer member U1 within thescope of the second variant of the regulation circuit 200b in accordancewith the invention T1 First transistor stage, realized as bipolar pnptransistor, for the level or potential offset stage provided within thescope of the second variant of the regulation circuit 200b in accordancewith the invention as signal transfer member U1 T2 Second transistorstage, realized as bipolar npn transistor, for the level or potentialoffset stage provided within the scope of the second variant of theregulation circuit 200b in accordance with the invention as signaltransfer member U1 U1 Signal transfer member in the feedback branch ofthe current I_(D) flowing through the power luminescent diodes D1, . . ., DN, tapped off at the second measurement resistance R4, to the controlinput of the first switching stage M1, the member for galvanicdecoupling (potential separation) of the voltage U_(R4) dropped at thesecond measurement resistant R4 and the control voltage U_(G) of thefirst switching stage M1, realized as opto-coupler diode (c.f. FIG. 2a)or as level or potential offset stage (c.f. FIG. 2b) V1 Rectifier fullbridge for rectifying the positive and/or negative half-waves of thea.c. current I_(NETZ) delivered from a current supply mains X_(L1)Inductive reactance of a coil L1, as ballast choke for filtering ofharmonics, connected in series to the high power luminescent diodes D1,. . . , DN, for extending the current flow duration of the currentflowing through the high power luminescent diodes D1, . . . , DN Z1Zener diode as voltage limiter for stabilization of the input voltageU_(Z1) at the output terminals 3 and 4 of the opto-coupler diode, levelor potential offset stage U1 μP Microprocessor for regulating the seriesresistor R3, constituted as a potentiometer for the purpose of dimmingthe high power luminescent diodes D1, . . . , DN

1.-24. (canceled)
 25. A current supply circuitry for at least oneluminescent diode having: at least one inductive reactance connected asa storage choke in series with the luminescent diode; switching stagesfor switching over between a charging or a discharging process occurringin the storage choke upon over-shooting or under-shooting of thresholdvalues of respective control voltages of the switching stages; and afree running current path, connected in parallel with the seriesconnection of the luminescent diodes and the storage choke, for at leasta part of the discharge current released by the storage choke to theluminescent diodes upon blocking of the first switching stage.
 26. Thecircuitry according to claim 25, comprising a first shunt measurementresistance for detecting the diode current flowing through theluminescent diodes during a charging process occurring in the storagechoke.
 27. The circuitry of claim 25, comprising a second shuntmeasurement resistance for detecting the diode current flowing throughthe luminescent diodes during a discharge process occurring in thestorage choke.
 28. The circuitry of claim 27, comprising a signaltransfer element for feeding back the current flowing through theluminescent diodes, tapped off at the second measurement resistance, tothe control input of the first switching stage, the member serving forgalvanic de-coupling of the voltage dropping at the second measurementresistance and the control voltage of the first switching stage.
 29. Thecircuitry according to claim 28, wherein the signal transfer elementemployed for potential separation is a level offset stage.
 30. Thecircuitry of claim 25, wherein a free-running diode in the free-runningcurrent path connected in connected anti-parallel to the series circuitof the luminescent diodes and the storage choke.
 31. The circuitry ofclaim 25, furthermore comprising a time dependent controller forswitching over between the charging and discharging processes occurringin the storage choke.
 32. A current supply circuitry for at least oneluminescent diode, having: at least one inductive reactance connected asstorage choke in series to the luminescent diode; a free running currentpath, connected in parallel to the series connection of the luminescentdiodes and the storage choke, for at least a part of the dischargecurrent released by the storage choke to the luminescent diodes uponblocking of the first switching stage; and time dependent controller forswitching over between the charging and discharging processes occurringin the storage choke.
 33. A method for regulating a current supply of atleast one luminescent diode comprising charging and discharging currentof an inductive reactance connected in series to the luminescent diodesas a storage choke, wherein responsive to charging and discharging,current flows as diode current through the luminescent diodes and isused for the generation of an alternating current varying periodicallyabout a settable direct current value.
 34. The method according to claim33, wherein a direct current offset constituting a middle value of aresulting triangular diode current is set by means of a suitabledimensioning of at least one shunt measurement resistance.
 35. Themethod according to claim 33, comprising: switching over by switchingstages between the charging or discharging occurring in the storagechoke upon over-shooting or under-shooting of threshold values ofrespective control voltages of the switching stages; and releasing atleast a part of the discharge current by the storage choke to theluminescent diodes upon blocking of the switching stages.
 36. Alight-emitting diode module, comprising an arrangement of seriesconnected light-emitting diodes, which are applied on a circuit board,wherein the light-emitting diode illumination module has a regulationcircuit for providing a constant current supply; and the constantcurrent supply comprises: at least one inductive reactance connected asa storage choke in series to the light-emitting diodes; a free runningcurrent path, connected in parallel to the series connection of thelight-emitting diodes and the storage choke, for at least a part of thedischarge current released by the storage choke to the light-emittingdiodes upon blocking of the first switching stage; and a time dependentcontroller for switching over between the charging and dischargingprocesses occurring in the storage choke.
 37. The light-emitting diodemodule of claim 36, wherein the light-emitting diodes are applied to thecircuit board in a Chip-On-Board technology.
 38. The light-emittingdiode module of claim 36, the light-emitting diode module isaccommodated in a transparent housing.
 39. The light-emitting diodemodule of claim 38, wherein Fresnel lenses, each in the form of a lensplate for the attainment of a bundled homogenous light distribution inthe region of the main emission directions, are positioned centrallyabove each light-emitting diode within the transparent housing.
 40. Thelight-emitting diode module of claim 38, wherein the inner sides of thetransparent housing, with the exception of the light emitting region,are of a thermally good conducting material, which on the outer side forheat discharge is covered over with an electrically non-conductingmaterial.
 41. The light-emitting diode module of claim 38, wherein thetransparent housing can be contacted with the aid of a plug, socketand/or connection cable light-emitting diod out of the housing to theside.
 42. The light-emitting diode module of claim 36 further includinga parabolic or funnel-shaped reflector of a reflector plate, formed of athermally-good conductive, highly reflecting material, which iselectrically insulated on the underside of the reflector, wherein thereflector is disposed around each light-emitting diode, and where thereflector is constructed to be placed around the light-emitting diodefrom above the circuit board.
 43. The light-emitting diode moduleaccording to claim 42, wherein each individual reflector is formed of aplastic having a mirrored inner side.
 44. The light-emitting diodemodule of claim 36, wherein the rear side of the circuit board is couplight-emitting diode to a cooling body which is constructed to transferheat arising from operation of the light-emitting diode illuminationmodule to the housing or a mounting.
 45. A method for producing thelight-emitting diode module of claim 36, comprising assembling thelight-emitting diode of the light-emitting diode illumination moduledirectly with a highly transparent polymer mass.
 46. The method of claim45, wherein assembling includes molding directly unhoused light-emittingdiodes with the polymer mass in an injection molding process and/or bymeans of a casting process.
 47. A method for producing the module ofclaim 36, wherein at least one light-emitting diode is a bluelight-emitting diode which produces white light by means of a colorconversion layer arranged above the light-emitting diode.